Internal combustion engine with two-stage turbo charging system

Abstract

An internal combustion engine is provided with an exhaust gas pipe for taking exhaust gases from the engine's combustion chamber and an intake pipe for supplying air to the combustion chamber. The engine includes a turbo charging system with a high-pressure turbine that interacts with a high-pressure compressor and a low-pressure turbine that interacts with a low-pressure compressor, for recovery of energy from the engine's exhaust gas flow and pressurizing of the engine's intake air. The high-pressure turbine is connected to the low-pressure turbine via a duct. An exhaust gas pressure regulator is located in the duct between the high-pressure turbine and the low-pressure turbine.

1. An internal combustion engine comprising
 an exhaust gas pipe for taking exhaust gases from a combustion chamber of the engine, 
 an intake pipe for supplying air to the combustion chamber, 
 a turbo charging system with a high-pressure turbine that interacts with a high-pressure compressor and a low-pressure turbine that interacts with a low-pressure compressor for recovery of energy from an exhaust gas flow of the engine and pressurizing of intake air of the engine, which high-pressure turbine is connected to the low-pressure turbine via a duct, and 
 an exhaust gas pressure regulator located in the duct between the high-pressure turbine and the low-pressure turbine, wherein the exhaust gas pressure regulator is self regulating and opens automatically when pressure upstream of the exhaust gas pressure regulator is above a predetermined pressure, the exhaust gas pressure regulator comprising a piston centered on, arranged to move in a direction parallel to, and obstructing flow along an axial centerline of the duct to regulate a flow area of the duct. 
 
     
     
       2. An internal combustion engine comprising
 an exhaust gas pipe for taking exhaust gases from a combustion chamber of the engine, 
 an intake pipe for supplying air to the combustion chamber, 
 a turbo charging system with a high-pressure turbine that interacts with a high-pressure compressor and a low-pressure turbine that interacts with a low-pressure compressor for recovery of energy from an exhaust gas flow of the engine and pressurizing of intake air of the engine, which high-pressure turbine is connected to the low-pressure turbine via a duct, and 
 an exhaust gas pressure regulator located in the duct between the high-pressure turbine and the low-pressure turbine, wherein the exhaust gas pressure regulator is self regulating by the engine's exhaust gas flow, wherein the low-pressure turbine is of an axial type, and the duct has a circular cross section that is formed of an outer wall that is symmetrical around an adds of rotation of the duct and that has a cross section that increases in a direction towards the low-pressure turbine, and a central part arranged concentrically inside the wall with a cross section that increases in the direction towards the low-pressure turbine. 
 
     
     
       3. The internal combustion engine as claimed in  claim 2 , wherein the central part is provided with a control piston that is mounted on the central part, the control piston being axially movable between the central part and the outer wall for regulation of a flow area of the duct. 
     
     
       4. The internal combustion engine as claimed in  claim 3 , wherein the control piston is movably mounted on a shaft that is attached to a stator ring that is mounted on an intake of the low-pressure turbine. 
     
     
       5. The internal combustion engine as claimed in  claim 4 , wherein the control piston is movable between two end positions against an effect of a spring device. 
     
     
       6. The internal combustion engine as claimed in  claim 5 , wherein the control piston is movable between an inactive opening position and an active closing position by an effect of a pressurized medium that acts in a direction opposite to a direction of a force of the spring device. 
     
     
       7. The internal combustion engine as claimed in  claim 6 , wherein the control piston and the shaft together form a circular chamber with variable displacement for a pressurized medium. 
     
     
       8. The internal combustion engine as claimed in  claim 7 , wherein the chamber is connected to a connection for pressurized medium on an outside of the duct via a duct for pressurized medium that extends through the shaft and the stator ring. 
     
     
       9. The internal combustion engine as claimed in  claim 3 , wherein the control piston is provided with a piston surface that is movable in an inner chamber in the central part and is acted upon by pressure upstream of the exhaust gas pressure regulator via a duct for pressure balancing of the control pressure of the exhaust gas pressure regulator. 
     
     
       10. The internal combustion engine as claimed in  claim 3  wherein the control piston is designed as an open cylinder with an outer wall surface that, in an inactive control position, forms an axial extension of the central part between the central part and the stator ring, and with an inner wall surface that, in an active control position, forms an axial extension of the outer wall between the outer wall and the central part.